Condensed Consolidated Statements of Cash Flows (Unaudited) $ in Thousands	9 Months Ended
	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Cash flows from operating activities:
Net income	$ 17,518	$ 17,383
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	150,881	144,441
Amortization of intangible assets	32,517	37,721
Deferred income taxes	3,083	(1,263)
Stock-based compensation expense	39,923	34,316
Loss on disposition of fixed assets	26,995	25,980
Other non-cash adjustments	7,077	5,658
Increase (decrease) in cash resulting from changes in operating assets and liabilities, net of effects of acquisitions:
Accounts receivable	26,673	2,171
Inventories	(9,752)	(20,149)
Other assets	(11,123)	(4,686)
Accounts payable	(7,827)	(8,659)
Accrued liabilities	34,219	(10,994)
Other liabilities	2,495	(2,429)
Net cash provided by operating activities	312,679	219,490
Cash flows from investing activities:
Purchase of property, equipment and satellites	(390,223)	(283,202)
Cash paid for patents, licenses and other assets	(56,013)	(52,495)
Payments related to acquisition of businesses, net of cash acquired	(16,528)	(3,908)
Other investing activities	(649)
Net cash used in investing activities	(463,413)	(339,605)
Cash flows from financing activities:
Payment of debt issuance costs	(6,677)	(803)
Proceeds from issuance of common stock under equity plans	22,403	20,318
Purchase of common stock in treasury (immediately retired) related to tax withholdings for stock-based compensation	(21,150)	(16,056)
Proceeds from common stock issued in public offering, net of issuance costs	503,061
Other financing activities	(1,146)	(1,142)
Net cash provided by financing activities	393,960	131,713
Effect of exchange rate changes on cash	(371)	3
Net increase in cash and cash equivalents	242,855	11,601
Cash and cash equivalents at beginning of period	42,088	52,263
Cash and cash equivalents at end of period	284,943	63,864
Non-cash investing and financing activities:
Issuance of common stock in satisfaction of certain accrued employee compensation liabilities	13,080	11,609
Capital expenditures not paid for	10,918	51,093
Issuance of common stock in connection with acquisition	4,988
Revolving Credit Facility [Member]
Cash flows from financing activities:
Proceeds from credit facility borrowings	90,000	175,000
Payments of revolving credit facility borrowings	(270,000)	(185,000)
Ex-Im Credit Facility [Member]
Cash flows from financing activities:
Proceeds from credit facility borrowings	77,469	139,396
Non-cash investing and financing activities:
Exposure fees on Ex-Im credit facility expected to be financed through Ex-Im credit facility	$ 8,505	$ 13,658